Exchange 2010 unable to access other users profile

We have just upgraded from exchange 2007 to exchange 2010 sp2. Since this has happened the admins are unable to access another users OUtlook profile. ie. in the past we were able to create an outlook profile for another user in order to access their mailbox (for example to set an oof). Since we moved to exch 2010 when we create another user's profile a username and password box comes up. Entering our domain admin credentials does not create the profile, only entering the user's username/password does the job. I have tried adding myself to the Exchange organisation role group and have also given myself full rights on every mailbox with this ps command:

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